# Higher Order Mode Entanglement in a Type II Optical Parametric Oscillator

## TL;DR

This paper demonstrates how optimizing the pump mode in a type II optical parametric oscillator enhances entanglement in first-order spatial modes, overcoming previous limitations in high order mode squeezing.

## Contribution

It is the first experimental report showing that pump mode optimization maximizes high order spatial mode entanglement in a type II OPO.

## Key findings

- Maximum entanglement achieved by optimizing pump mode
- HG10 mode threshold reached without HG00 oscillation
- HG10 entanglement increased by 53.5% over standard pumping

## Abstract

Nonclassical beams in high order spatial modes have attracted much interest but they exhibit much less squeezing and entanglement than the fundamental spatial modes, limiting their applications. We experimentally demonstrate the relation between pump modes and entanglement of first-order HG modes (HG10 entangled states) in a type II OPO and show that the maximum entanglement of high order spatial modes can be obtained by optimizing the pump spatial mode. To our knowledge, this is the first time to report this. Utilizing the optimal pump mode, the HG10 mode threshold can be reached easily without HG00 oscillation and HG10 entanglement is enhanced by 53.5% over HG00 pumping. The technique is broadly applicable to entanglement generation in high order modes.